Summary of Work: The objective of this project is to develop a package of brief, safe and reliable measures of exercise tolerance that, in total, is broadly applicable and highly discriminating in population studies of older persons. The first phase of testing and evaluation has been completed at the Baltimore Veteran's Administration Medical Center through an interagency agreement (Y01-AG-4-0260). The following tests were administered on two occasions 7 to 10 days apart to a volunteer sample of 50 men and women age 54-80 years, 24 of whom had peripheral arterial disease: (1) timed usual and fast pace 4-meter walks; (2) timed usual and fast pace 20-meter walks; (3) 6-minute usual pace corridor walk; (4) seated step-test; and (5) treadmill walk. Heart rate at work, recovery heart rate, and blood pressure were measured. Two questionnaires were also piloted; (1) a refinement of Taylor's Leisure Time Physical Activity questionnaire and (2) a measure of physical function that includes ease of performance and level of fatigue as well as difficulty in performing higher order functional tasks. Preliminary results were presented at GSA, November 1995 and a manuscript comparing performance across measures of exercise tolerance is under review. Analyses of the reliability and validity of questionnaires are ongoing. The original socpe was completed March 1996, under budget and a second phase of testing commenced October 1996 to evaluate a modification of the 6,-minute walk, the HEALTH ABC Long Distance Corridor Walk (LDCW). Key features are the 2-minute warm-up walk that also serves as a stepped-down test and the focus on distance (400m) instead of time (e.g., 6 minutes). Twenty men and women age 70 to 79 did the LDCW and 6-minute walk with a 15-minute rest between, during which they were administered a revised version of the physical activity questionnaire used in phase one. Test order alternated between subjects. Findings were presented at the 50th Annual Scientific Meeting of the Gerontological Society of America, November 1997. A manuscript is in preparation.